Minimally Invasive Approach to Pediatric Pancreatic Disorders



Fig. 40.1.
A pancreatic pseudocyst 5 weeks after complete pancreatic transection. Note the apposition of the pseudocyst wall to the posterior stomach, making the lesion now amenable to cystogastrostomy.





Technique


Regardless of the indication for surgery, this chapter will focus on the techniques used in the most common indication for intervention, pseudocyst, and the most common operation for non-pseudocyst lesions, distal pancreatectomy.


Anatomy


The pancreas in divided into a head, body, and tail, with the body overlying the L1 vertebrae. This largely retroperitoneal structure sits with the head in the curve of the duodenum and the body and tail behind the stomach. The splenic artery follows the superior aspect of the gland from midline laterally, supplying short arterial branches along its length. Additional arterial supply arises from the inferior pancreatic artery, also a branch off the splenic artery. The splenic vein courses across the lower aspect of the tail as it heads more superiorly before merging with the superior mesenteric vein and entering the portal vein posterior to the pancreatic head. It drains the body and tail of the pancreas.

The duct of Wirsung, or main pancreatic duct, drains the length of the pancreas, emptying into the duodenum at the ampulla of Vater in conjunction with the common bile duct. The accessory duct of Santorini drains the dorsal bud and can have its own minor papilla for drainage. Pancreatic divisum occurs after failure of the embryonic ventral and dorsal pancreatic buds to properly fuse.


Positioning


Patients are typically positioned supine or in a partial right decubitus position with a roll behind the left lower rib cage.


Instruments


A standard 5-mm laparoscopic instrument tray , three to four 5-mm ports, a 12-mm port for a stapler, a 30-degree 5-mm laparoscope, a 5-mm clip applier, and an energy device, such as ultrasonic shears or other tissue-sealing device, are necessary. A laparoscopic biopsy needle for aspiration may be required for pseudocyst localization. One or more 45-cm vascular staple loads for a laparoscopic stapler are needed for either creation of the cystogastrostomy or transecting the pancreas. An endoscope, pediatric or adult, can be used for hybrid cystogastrostomy approaches, while an adult endoscope with a larger working channel is needed for purely endoscopic approaches.


Laparoscopic Internal Drainage of Pseudocysts


Laparoscopic cystogastrostomy for the treatment of pancreatic pseudocysts in the pediatric population has been done for nearly a decade [28]. A transumbilical laparoscope allows visualization of the anterior gastric wall with pneumoperitoneum. Following this, two trocars are inserted through the abdominal wall and anterior gastric wall such that they access the gastric lumen. This can be facilitated by the placement of stay sutures or T fasteners through the abdominal and anterior gastric walls for apposition of the two layers as well as insufflation of the stomach with gas through an NG tube. The pneumoperitoneum can then be released and a small amount of insufflation at a low pressure be placed intragastric for visualization through the ports. The posterior gastric wall will commonly have a protrusion identifying the site of the pseudocyst. After confirmation of pseudocyst location through needle aspiration with a laparoscopic device, cautery or an alternative energy device is used to create a posterior gastrotomy and enter the pseudocyst. Clear pancreatic fluid typically drains. For a hybrid approach, one of the transgastric trocars can be replaced by the endoscope for visualization, insufflation is accomplished through the endoscopic port, and an endoscopic needle knife can be used for aspiration and gastrotomy. A stapled anastomosis is performed to widen the opening and one or more firings can be utilized. The gastric distension is then relieved and pneumoperitoneum reestablished. The anterior gastrotomies can be closed by pulling the transgastric trocars back to an intraperitoneal location and either stapling the holes closed or hand suturing them. Laparoscopic drainage of pediatric pancreatic pseudocysts is proving to be a beneficial minimally invasive procedure providing definitive drainage. A nasogastric tube may or may not be left overnight and a contrast study prior to oral intake is not typically required in the absence of clinical concern for a leak. Oral intake can be initiated in less than 24 h or upon resolution of any ileus. The postoperative recovery time is significantly shorter than other treatment options, a notable benefit [28, 29]. The most common complications are anastomotic bleeding, leak, pancreatitis, infection, and premature closure.


Endoscopic Internal Drainage


The first case of pediatric pancreatic pseudocyst endoscopic drainage was reported by Wiersema et al. in 1996 [30]. There are two approaches to endoscopic drainage of pancreatic pseudocysts: transmural drainage or transpapillary drainage. Transmural drainage is indicated if the pseudocyst is in direct opposition to the stomach or duodenum. The pseudocyst must visibly bulge into the gastric or duodenal wall [31]. Transpapillary drainage is indicated if endoscopic retrograde cholangiopancreatography shows pseudocyst connection with the main pancreatic duct, and internal stenting is technically feasible [32]. However, cysts suspected to contain thick material or debris may be best managed by alternate techniques.

Endoscopic transmural drainage is accomplished with a flexible endoscope and a diathermy needle knife to puncture the pseudocyst through the posterior wall of the stomach. Over guidewire dilation enlarges the communication between the stomach and the pseudocyst. Both double J stents and double pigtail stents are used to maintain patency while the pseudocyst resolves [31] (Fig. 40.2). The AXIOS Stent and Electrocautery Enhanced Delivery System (Boston Scientific) was approved by the FDA in 2013 specifically for transgastric endoscopic drainage of pancreatic pseudocysts. Diet can be resumed post procedure after concern for procedural complications has passed. There are associated complications with internal endoscopic drainage. Bleeding, infection leading to abscess formation, stent dysfunction, pancreatitis, and pseudocyst recurrence are the main concerns. Most stents remain in place for 3–8 weeks before endoscopic removal.

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Fig. 40.2.
Fluoroscopic image of a stent placed endoscopically for treatment of a pancreatic pseudocyst in a 9-year-old boy following trauma.


Laparoscopic Distal Pancreatectomy


A 5-mm port is placed in the umbilicus and pneumoperitoneum is established. The remaining trocar positions are variable based on the patient size, but should allow access to the left upper quadrant, similar to a laparoscopic splenectomy. Port placement may vary depending on whether the surgeon elects to stand the patient’s right side or between the legs. Generally, one port in the left upper quadrant and one in the medial right upper quadrant can complement an optional epigastric port. All can be 5-mm in size until time for transection of the pancreas with an endoscopic stapler, at which point either the epigastric or a left upper quadrant port needs to be transitioned to a 12-mm port to accommodate the device. The gastrocolic ligament is opened, taking care to spare the gastroepiploic and short gastric vessels. A retractor in the epigastric port or transabdominal sutures to elevate the inferior aspect of the stomach permits visualization of the distal pancreas. In the setting of inflammation, some dissection may be required along the posterior wall of the stomach to elevate it off of the pancreas. If available, endoscopic ultrasound can be used at this time to either identify the lesion and a negative margin and/or assess the location of the vessels and their relationship to the mass. Dissection continues at the inferior aspect of the tail of the pancreas. Elevating the pancreas superiorly allows clearing of the relatively avascular posterior wall pancreas from inferior to superior. When the tail of the pancreas can be clearly identified, the splenic vein can similarly be seen posteriorly. The pancreatic tail can then be retracted superomedially to allow division of branches between the vein and the pancreas to be divided with an energy device. As the vein is left behind, small arterial branches from the splenic artery may become visible and be similarly divided. If the pancreas has been divided due to trauma, the distal remnant will often be free now. If the pancreatic duct is visible at the transection site, suture closure of the duct and/or nearby tissue can minimize subsequent leak [33].

If the distal pancreatectomy is for a mass lesion located in the tail, it can be helpful to carefully create a window around the pancreas medial to the mass and pass a ¼-in. penrose drain around the body of the pancreas for retraction. This can make careful separation of the pancreas and/or mass from the splenic vessels easier through a medial to lateral approach when splenic preservation is intended. Alternatively, once the vessels are safely away, an endoscopic stapler with vascular loads can be used to transect the pancreatic parenchyma before proceeding laterally (Fig. 40.3).

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Fig. 40.3.
The pancreatic body has been transected medial to the mass and dissection will now proceed laterally to the tail. From Palavivelu C, Shety R, Jani K, et al. Laparoscopic distal pancreatectomy . Results of a prospective non-randomized study from a tertiary center. Surg Endoscopy 2007 Mar:21(3):373–77. Reprinted with permission from Springer.

A closed suction drain is commonly placed in the pancreatic bed and some surgeons place fibrin glue over the cut edge of the residual pancreas. The resected pancreas can be placed in a laparoscopic bag and withdrawn through an enlarged port site, with or without morcellation, or through a Pfannenstiel incision for malignancy. While splenic artery and vein preservation are ideal, this is significantly more technically difficult than division of these vessels at the proximal and distal aspects of the pancreas. For malignant lesions with adherence to the splenic vessels, splenic vessel preservation should be avoided, though the spleen may remain in situ and viable based on the short gastrics. In addition to energy devices, judicious use of clips can help control the vasculature. The spleen, if preserved, should be inspected for viability, with consideration given to performing a splenectomy if lacking perfusion. Even if the spleen is successfully preserved at the time of surgery, splenic vein thrombosis can complicate the postoperative period. Additionally, in the adult population, if the splenic vein is ligated, the splenic artery is also ligated to prevent segmental portal hypertension [34]. Uncontrolled bleeding, inability to identify the pathology, inadequate margins, and inadequate exposure are all indications for conversion to open techniques.

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Oct 25, 2017 | Posted by in PEDIATRICS | Comments Off on Minimally Invasive Approach to Pediatric Pancreatic Disorders
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